The present invention relates to a process for extraction of piperine from Piper species such as Piper nigrum, Piper retrofractum, Piper longum, Piper schmidtii. This method is particularly related to the extraction of piperine using aqueous hydrotrope solutions for the first time.
Piperine (C17H19O3N) is the major constituent of black pepper (Piper nigrum) and is used extensively as a spice, condiment, insecticide and for medicinal purposes. It has shown potent chemoprotective effect against procarcinogens (Reen and Rashmet, J. Ethnopharmacol., 1997, 58(3), 165-173). The extracts of Piper nigrum are found to have a hypercoagulative effect in vitro., they lessen the clotting time by accelerating the thrombin activation and lowering the heparin level in the clotting systems. (Hasselstorm et.a)., Food Res., 1954 19, 373). They are valued for their rubefacient properties and hence used as local application for sore throat, piles and some skin diseases (Wealth of India, Raw Materials, Vol.III, pg. 110).
The concentration of piperine is about 6% to 9% in Piper nigrum, 4.0% in Piper longum fruits and 4.5% in Piper retrofractum. 
H. Staudinger and H. Schnieider [Ber; 56, 699(1923)] described a process for the extraction of piperine from Piper nigrum fruits, wherein the alkaloid was extracted using ethanol and the extract was treated with aqueous sodium hydroxide to remove all the resinous matter. Other solvents used for extraction are petroleum ether and dichloromethane. The extraction of piperine into these organic solvents is not selective as other compounds like gums, polysaccharides and resins are extracted reducing the purity of piperine. The post extraction processing to purify piperine is cumbersome and uneconomical. A liquid pepper composition containing pepper in a concentrated form has been prepared by extracting the pepper fruits with acetone and subsequent treatment with anhydrous lactic acid (Wealth of India, Raw Materials, Vol. III, pg. 111).
Vidal, J. P. and Richard, H., (Scientific .Aliments 1987, 7(3), 481-98) outlines a procedure for the production of black pepper oleoresins by dense carbon dioxide extraction or carbon dioxide+ethanol extraction. The extract contains 16.7% essential oils and 42.2% piperine which was very close to that obtained by dichloromethane as solvent.
Hans J. (3,706594 German. Offen. DE 28/02/1987, Beutler) described a process wherein gaseous carbon dioxide under supercritical conditions is passed downward through a packed bed of pulverised pepper and the loaded solvent is then expanded in a downstream separator for release of the extracted material. However, this process using supercritical fluid extraction is not economical and still a further solvent extraction step is essential for obtaining pure piperine.
Most of these prior art processes relate to the extraction of Piper nigrum oleoresin containing piperine and other volatile oils. Piperine containing oleoresin is then solvent extracted and recrystallised to obtain pure piperine. These conventional processes are carried out using a number of steps which often present difficult operating conditions and result in a high cost of production.
The main object of the present invention is to provide a cost effective process for the extraction of piperine from Piper species in a substantially pure form using the phenomena of hydrotropy. The approach is to find a suitable hydrotrope for selective extraction of piperine from Piper species followed by dilution of the extract phase to precipitate piperine in pure form.
Another object is to provide a two step process for the selective extraction of phytochemicals like piperine exploiting the ability of hydrotropes to dissolve the otherwise water insoluble organic compounds in aqueous solution.
A further object is to provide a process for the recovery of piperine from the solution by simple dilution with water as most of the piperine precipitates out.
Still another object of the invention is to provide a process for the recovery of piperine from aqueous hydrotrope solution by extraction with organic solvents followed by de-solventisation.
Yet another object of the present invention is to provide a process for the extraction of piperine from Piper nigrum in the first step without using an organic solvent or excessive temperature to retain the purity of piperine.
The invention provides a novel two-step process for the extraction of piperine from plants of piper species using aqueous hydrotrope solution.
Accordingly the present invention provides a process for extraction of piperine of Formula 1 from the fruit of Piper species comprises, said process comprising the steps of: 
(i) contacting the fruit of piper species with aqueous hydrotrope solution at a temperature in the range of 0-100xc2x0 C. and separating the solution from the solid residue by known methods, and.
(ii) recovering the piperine from the solution obtained at the end of step (i) by known methods.
In an embodiment, piperine is recovered from the aqueous solution of hydrotrope obtained in step (i), after dilution with water so as to bring the concentration of hydrotrope sufficiently low to precipitate piperine from the solution in solid form and separating the precipitated piperine from the solution obtained, followed by washing with water or without dilution, by extraction with organic solvent selected from the group comprising aromatic hydrocarbons, aliphatic hydrocarbons, ethers, esters, ketones, amides, alcohols or mixtures thereof.
The dried fruits of Piper species such as Piper nigrum, Piper longum, Piper retrofractum, Piper schmidtii in pulverised form, preferably in the mesh size of 5 to 300 are brought in intimate contact with an aqueous solution of hydrotrope in the form of a slurry in a stirred vessel or in a column in which the coarse Piper species powder is packed and the solution passes over it. In the process of invention when the contacting is done in the stirred vessel the Piper species powder is added to the aqueous hydrotrope solution. After the aforementioned components are brought together, the mixture which is usually in the form of a slurry, is agitated for a period sufficient for the extraction of piperine to take place. A typical mixing time is in the range of 15 minutes to 24.00 hours depending upon the concentration of hydrotrope and the speed of agitation. The mixing is conducted at a selected temperature ranging from 0xc2x0 C.-100xc2x0 C. preferably at room temperature of 30xc2x0 C. and atmospheric pressure.
The Plants of Piper species for the extraction of piperine is selected from the group comprising Piper nigrum, Piper longum, Piper retrofractum, and Piper schmidtii. 
The term xe2x80x9chydrotropexe2x80x9d indicates short alkyl chain water soluble amphiphillic compounds. The hydrotrope is selected from the group comprising sodium, potassium, calcium, ammonium, magnesium salts of alkyl benzene sulfonates, such as benzene sulfonate, toluene sulfonate, xylene sulfonate, ethyl benzene sulfonate, styrene sulfonate, pseudocumene sulfonate, mesitylene sulfonate, propyl benzene sulfonate and butyl benzene sulfonate; alkyl polyglycol sulfates and phosphates such as methyl cellosolve sulfate, ethyl cellosolve sulfate, propyl cellosolve sulfate, butyl cellosolve sulfate, pentyl cellosolve sulfate, hexyl cellosolve sulfate and the corresponding phosphates with sodium, potassium, and calcium counterions; methyl diglycol sulfates, ethyl diglycol sulfates, propyl diglycol sulfates, butyl diglycol sulfates, pentyl diglycol sulfates, hexyl diglycol sulfates and phosphates salts of sodium, potassium, calcium and ammonium counterions; substituted aromatic carboxylates such as hydroxybenzotaes, toluates, chlorobenzoates, nitrobenzoates, alkyl benzene carboxylates with sodium, potassium, calcium and ammonium counterions; substituted phenates, such as hydroxyphenates, chlorophenates, alkyl phenates, naphthols; naphthalene carboxylates and substituted naphthalene carboxylates such as hydroxy naphthalene carboxylates.
After the mixing the solid residue is separated from the solution by decantation, filtration or centrifugation. The separated residue is washed with water and the washing is combined with filtrate or the filtrate is used as such for the recovery of piperine.
The filtrate is diluted with water to bring the concentration of hydrotrope low enough to precipitate piperine from the solution. The dilution is done at a temperature in the range of 0xc2x0-80xc2x0 C. preferably in the range of 20xc2x0-30xc2x0 C. The precipitated piperine is separated from the solution by decantation or filtration or centrifugation. The piperine is washed with water and dried. The hydrotrope solution recovered during this step is concentrated and recycled.
In another embodiment the filtrate obtained after the step (i) is subjected to extraction with an organic solvent for recovery of piperine from the aqueous solution of hydrotrope after dilution of the hydrotrope solution with water or without dilution. The organic solvent selected for the extraction should be immiscible with water and is selected from the group comprising aromatic hydrocarbons, aliphatic hydrocarbons, halogenated hydrocarbons, ethers, esters, alcohols, amides or mixtures thereof.